The invention discloses a monocrystalline silicon wafer with a rounded pyramid structure and a preparation method, and mainly relates to the field of monocrystalline texturing. The preparation methodcomprises the steps of pre-cleaning, texturing, rounding treatment, hydrofluoric acid cleaning, slow pulling, drying, and the like. In the rounded treatment process, respective characteristics of nitric acid CP and ozone CP are integrated. Pyramid rounding treatment is performed on a textured silicon wafer by using the scheme, so that the pyramid top and the pyramid valley are enabled to be smooth, the defect state density can be reduced when the amorphous silicon film is deposited, the passivation quality of the silicon wafer can be enhanced, the minority carrier lifetime can be prolonged, and thus higher cell conversion efficiency can be obtained.